Hydraulic control valve

ABSTRACT

A hydraulic control valve is provided which can amplify the pilot flow controlled a pilot valve coupled to the control valve. Orifices are inserted into the pilot and main flows so that the pressure difference or drop across these orifices may be transmitted across a spool in order to control the main flow in proportion to the pilot flow which in turn is controlled by the pilot valve.

United States Patent 1 1 Murata et a1.

1 1 3,884,253 1451 May 20, 1975 1 HYDRAULIC CONTROL VALVE [75]Inventors: Hikaru Murata; Yasuji Umeda;

Yasusada Sakurai; Yasuo Doi, all of Kamo, Japan [73] Assignee:Kayabakogyokabushikikaisha,

Tokyo. Japan [22] Filed: Dec. 29, 1972 [21] App]. No.: 319.306

[30] Foreign Application Priority Data Dec. 29. 1971 Japan 46-32331 Feb.18. 1972 Japan 47-16452 Feb. 26. 1972 Japan 47-20021 [52] US. Cl..l37/ll0; 91/443; 137/501 [51] Int. Cl. G05d 7/01 [58]Fie1dofSearch...91/447;137/84; 110; 116; 102; 137/486; 489; 501; 503;625.6

[56] References Cited UNITED STATES PATENTS 2.053.330 9/1936 Fitch137/110 2.495.785 1/1950 Stephens 91/447 X 2.665.704 l/1954Kanuch................. 137/110 2.893.415 7/1959 Arcnhoid et a1 137/102X 2.990.847 7/1961 Absalom 137/489 3.266.380 8/1966 Eige 137/84 X3.470.896 10/1969 Werter.... 137/110 3.587.619 6/1971 Krechel 137/1 16Primary Examiner-Robert G. Niison Attorney, Agent. or Firm-Saul Jecies13 Claims, 63 Drawing Figures PATENTEU mzoms 3, 884.253

sum {1 SF 40 PATENIED umzoms SHEET [23F 40 FIG.4

PATENTED W20 I975 3. 884, 25 3 SHEET 133mm FIG.5

Ill/A? FIG-7 FATENTED HAY 2 01975 SHEET ESBF 4O FIG.8

PATENTED 884. 253

SHEET 07 0F 40 FlG.9

PATENTEI] HMZOIBTS FIG. l3

PATENTEU W20975 884,253 SHEET 13GF 10 PATENTEUHAYZUEYS 3. 884, 253

SHEET mar 40 PATENTEU 3.884.253

SHEET 1s BF 40 FIG. l8

PATENTEI] MAY 2 01975 SHEET 17UF 1O FIG. 2|

1. A hydraulic control valve, comprising a valve body having anelongated chamber, a main flow input port and a main flow output portwhich both communicate with said chamber; a valve spool having a hollowinterior which communicates with said chamber at one axial end of saidspool, and a circumferential wall provided with an opening whichcommunicates with said hollow interior, said spool being axiallyslidable in said chamber between a normal position in which said openingis out of communication with both of said ports, and two operatedpositions in each of which said opening is in communication with arespective one of said ports; an external port formed in said valve bodyand communicating with said chamber adjacent said one axial end of saidspool; a pilot flow passage in said valve body, bypassing Said chamberand having one open end communicating with the exterior of said valvebody and another open end communicating with said external port; orificemeans interposed in said pilot flow passage intermediate said one endand said other end thereof; and aperture means communicating with saidchamber adjacent the other end of said valve spool, and with said pilotflow passage intermediate said orifice means and said one end, so that apressure difference which develops in said pilot flow passage acrosssaid orifice means acts upon said ends of said valve spool.
 2. A controlvalve as defined in claim 1, wherein said input and output ports areused as common input and output ports; and further comprising anadditional valve spool, pilot flow passage, orifice means and externalport similar to the previously mentioned ones and also disposed in saidcontrol valve, whereby a pair of control valve units are incorporated insaid control valve.
 3. A control valve as defined in claim 2, furthercomprising additional orifice means interposed between said input andoutput ports.
 4. A control valve as defined in claim 3, wherein some orall of said orifice means may have their cross-sectional areas varied byoperation from the exterior of said control valve.
 5. A control valvecomprising a valve body; an internal passage in said valve body andhaving opposite end portions; an external input port and an externaloutput port formed in said valve body and each communicating with saidinternal passage; a pilot port formed in said valve body andcommunicating with said passage; spool means having opposite axial endsand being shiftable in said internal passage intermediate said endportions between a normal position in which it prevents communicationbetween said external ports, and two operated positions in which itcommunicates a respective one of said external ports with said pilotport; a pilot flow passage formed in said valve body and bypassing saidinternal passage and said spool means, said pilot flow passagecommunicating with said opposite end portions adjacent said oppositeaxial ends of said spool means, said pilot flow passage having an inletfor a pilot flow at the exterior of said valve body; and orifice meansinterposed in said pilot flow passage so that a pressure difference maydelvelop across said orifice means and is transmitted to said oppositeaxial ends of said spool means.
 6. A hydraulic control valve, comprisinga valve body having a cylindrical valve chamber; port meanscommunicating with said valve chamber and defining two paths for a mainfluid flow which pass through said valve chamber and through one endthereof; a hollow valve spool received in said valve chamber andslidable therein between positions in which it completes and interruptssaid main fluid flow paths; a passage defining a pilot fluid flow pathwhich bypasses said valve chamber; restricted orifice means interposedin said pilot fluid flow path; restricted orifice means in said mainfluid flow paths located at said one end of said valve chamber; andconduit means for joining the fluid flow of said pilot fluid flow andthe fluid flow of said main fluid flow adjacent said restricted orificemeans for said main fluid flow paths, for controlling the displacementof said valve spool and the volumetric flow of fluid in the main fluidflow paths as a function of the difference between the pressure dropswhich occur in the fluid flows across said restricted orifice means. 7.A hydraulic control valve, comprising a valve body having a cylindricalvalve chamber; ports means communicating with said valve chamber anddefining two paths for a main fluid flow which pass alternately inopposite directions through said valve chamber and through one endthereof; a hollow valve spool received in said valve chamber andslidable therein between positions in which it completes and interruptssaid main fluid flow paths; a passage defining a pilot fluid flow pathwhich bypasses said valve chamber; restricted orifice means interposedin said pilot fluid flow path; restricted orifice means in said mainfluid flow paths located at said one end of said valve chamber; andconduit means for joining the fluid flow of said pilot fluid flow andthe fluid flow of said main fluid flow adjacent said restricted orificemeans for said main fluid flow paths, for controlling the displacementof said valve spool and the volumetric flow of fluid in the main fluidflow paths as a function of the difference between the pressure dropswhich occur in the fluid flows across said restricted orifice means. 8.A hydraulic control valve, comprising a valve body having a cylindricalvalve chamber; port means communicating with said valve chamber anddefining a main fluid flow path which passes through said valve chamberand through one end thereof; a hollow valve spool received in said valvechamber and slidable therein between positions in which it completes andinterrupts said main fluid flow path; passage means in said valve body,bypassing said valve chamber and defining a pilot flow path whichcommunicates with said main flow path in the region of said one end ofsaid valve chamber; a first restricted orifice in said main flow path atsaid one end of said valve chamber, intermediate the latter and saidpilot flow path; a second, damper orifice communicating the other end ofsaid valve chamber with said pilot flow passage; and a third orifice insaid pilot flow path intermediate said damper orifice and said main flowpath.
 9. A hydraulic control valve, comprising a valve body having acylindrical valve chamber; port means including a first and a secondexterior port, and a third port which communicates with said valvechamber, said first and second ports defining a first path for a firstmain fluid flow, and said first and third ports defining a second pathfor a main fluid flow which passes through said valve chamber andthrough one end thereof; a hollow valve spool received in said valvechamber and slidable therein between positions in which it completes andinterrupts said second main fluid flow path; a passage defining a pilotfluid flow path which bypasses said valve chamber; first restrictedorifice means interposed in said pilot fluid flow path; secondrestricted orifice means in said second main fluid flow path located atsaid one end of said valve chamber; and conduit means for joining thefluid flow of said pilot fluid flow and the fluid flows of both of saidmain fluid flows adjacent said second restricted orifice means, forcontrolling the displacement of said valve spool and the volumetric flowof fluid in the main fluid flow paths as a function of the differencebetween the pressure drops which occur in the fluid flows across saidrestricted orifice means.
 10. A hydraulic control valve, comprising avalve body having a cylindrical valve chamber; port means including afirst and a second port which communicate with one another to form afirst main fluid flow path, a third and fourth port both communicatingvia said valve chamber with said first port and defining second andthird main fluid flow paths which pass through said valve chamber andthrough one end thereof; a hollow valve spool received in said valvechamber and having a pair of axially spaced apertures in itscircumference, said valve spool being slidable in said valve chamberbetween a position in which communication between said apertures andsaid third and fourth ports is interrupted, a position in which one ofsaid apertures communicates with said third port, and a position inwhich the other of said apertures communicates with said fourth port; apassage defining a pilot fluid flow path which bypasses said valvechamber; first restricted orifice means interposed in said pilot fluidflow path; second restricted orifice means in said second and third mainfluid flow paths located at said one end of said valve chamber; andconduit means for joining the fluid flow of said pilot fluid flow andthe fluid flows of all of said main fluid flows adjacent said restrictedorifice means for said second and third main fluid flow paths, forcontrolling the the displacement of said valve spool and the volumetricflow of fluid in the main fluid flow paths as a function of thedifference between the pressure drops which occur in the fluid flowsacross said restricted orifice means.
 11. A hydraulic control valve,caomprising a valve body having a cylindrical valve chamber; a singleport communicating with said valve chamber and defining a path for amain fluid flow which passes through said valve chamber and through oneend thereof; a hollow valve spool received in said valve chamber andhaving a circumferential wall formed with an opening, said valve spoolbeing slidable in said valve chamber between a position in which saidopening communicates with said port, and another position in which saidopening is out of communication with said port; biasing means biasingsaid valve spool to said other position; a passage defining a pilotfluid flow path which bypasses said valve chamber; restricted orificemeans interposed in said pilot fluid flow path; restricted orifice meansin said main fluid flow path located at said one end of said valvechamber; and conduit means for joining the fluid flow of said pilotfluid flow and the fluid flow of said main fluid flow adjacent saidrestricted orifice means for said main fluid flow path, for controllingthe displacement of said valve spool against the force of said biasingmeans and the volumetric flow of fluid in the main fluid flow path as afunction of the difference between the pressure drops which occur in thefluid flow across said restricted orifice means.
 12. A hydraulic controlvalve, comprising a valve body having a cylindrical valve chamber; portmeans including a pair of axially spaced ports communicating with saidvalve chamber and defining two paths for main fluid flows which passthrough said valve chamber and through one end thereof; a hollow valvespool received in said valve chamber and having a circumferential wallformed with a pair of axially spaced openings, said valve spool beingslidable in said valve chamber between a position in which said openingsare both out of communication with said ports, and positions in whichrespective ones of said openings communicate with the respective ports;a passage defining a pilot fluid flow path which bypasses said valvechamber but communicates with one of said ports; restricted orificemeans interposed in said pilot fluid flow path; restricted orifice meansin said main fluid flow path located at said one end of said valvechamber; and conduit means for joining the fluid flow of said pilotfluid flow and the fluid flows of said main fluid flows adjacent saidrestricted orifice means for said main fluid flow paths, for controllingthe displacement of said valve spool and the volumetric flow of fluid inthe main fluid flow paths as a function of the difference between thepressure drops which occur in the fluid flows across said restrictedorifice means.
 13. A hydraulic control valve, comprising a valve bodyhaving a cylindrical valve chamber; port means communicating with saidvalve chamber and defining a path for a main fluid flow which passesthrough said valve chamber and through one end thereof; a hollow valvespool received in said valve chamber and slidable therein betweenpositions in which it completes and interrupts said main fluid flowpath; a passage defining a pilot fluid flow path which bypasses saidvalve chamber; restricted orifice means interposed in said pilot fluidflow path; restricted orifice means in said main fluid flow path locatEdat said one end of said valve chamber; and conduit means for joining thefluid flow of said pilot fluid flow and the fluid flow of said mainfluid flow adjacent said restricted orifice means for said main fluidflow path, for controlling the displacement of said valve spool and thevolumetric flow of fluid in the main fluid flow path as a function ofthe difference between the pressure drops which occur in the fluid flowsacross said restricted orifice means.